1. Field of the Invention
The present invention relates to a bonding apparatus which bonds semiconductor pellets to leads of lead frames or leads installed on a film carrier, and more particularly, to a device for adjusting the raised position of the bonding stage of the bonding apparatus.
2. Prior Art
For example, the apparatus disclosed in Japanese Patent Application Laid-Open (Kokai) No. 5-259219 is known as a bonding apparatus which bonds semiconductor pellets to leads installed on a film carrier.
In this type of bonding apparatus, it is necessary to change the raised position of the bonding stage (on which the semiconductor pellets are carried) in order to adjust the clearance between the semiconductor pellets and the leads (which are bonded) in cases where the type of product to be handled is changed. The adjustment device which is used to adjust the raised position of the bonding stage includes: an adjustment means, which adjusts the relative amount of vertical movement of the bonding stage with respect to the raising-and-lowering drive means that raises and lowers the bonding stage, and a detection means, which detects the amount by which the bonding stage is moved up and down by the adjustment means.
With the bonding stage set at a raised position, the bonding stage is pushed up by the adjustment means so that the bumps on the semiconductor pellet are caused to contact the leads, and the detected value obtained by the detection means in this state is taken as a standard value. Then, with the leads being contacted BY the bumps, the bonding stage is lowered by the adjustment means so that the detected value obtained by the detection means becomes a prescribed value relative to the standard value. The clearance between the leads and the bumps on the semiconductor pellet is thus adjusted to a prescribed amount.
Accordingly, in the prior art described above, two operations are required: one for rasing the bonding stage by manually operating the adjustment means so that the bumps on the semiconductor pellet are brought to contact the leads, the other for lowering the bonding stage by operating the adjustment means so that the detected value obtained by the detection means becomes a prescribed value. Furthermore, these operations must be performed each time there is a change in the type of product to be handled.
Accordingly, it is impossible to respond quickly to changes in the type of product to be handled. Furthermore, since observation of the conditions of contact of the bumps on the semiconductor pellet with the leads is accomplished by visual inspection, and since this operation is performed each time when the type of product to be handled is changed, some unexpected differences may occur in the adjustment as a result of individual differences of the workers. As a result, consistent quality bonding is not accomplished.